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Upstream Bio (UPB) director option grant held for Enavate Sciences, LP

Filing Impact
(Neutral)
Filing Sentiment
(Neutral)
Form Type
4

Rhea-AI Filing Summary

Upstream Bio, Inc. director Harold Edward Fleming reported a grant of stock options covering 17,096 shares of common stock, with an exercise price of $6.69 per share and expiration on June 8, 2036. The options vest in full on June 9, 2027 or the next annual stockholder meeting and are held for the benefit of Enavate Sciences, LP, with Mr. Fleming disclaiming beneficial ownership.

Positive

  • None.

Negative

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Insider Fleming Harold Edward
Role null
Type Security Shares Price Value
Grant/Award Stock Option (Right to Buy) 17,096 $0.00 --
Holdings After Transaction: Stock Option (Right to Buy) — 17,096 shares (Direct, null)
Footnotes (1)
  1. The shares underlying this option shall vest in full upon the earlier of (i) June 9, 2027 and (ii) the date of the next Annual Meeting of Stockholders of the Issuer, subject to the Reporting Person's continued service on such vesting date. Mr. Fleming has agreed to receive and hold for the benefit of Enavate Sciences, LP, any securities granted to him for his service as a director on the Issuer's board of directors. As such, Mr. Fleming disclaims beneficial ownership of, and all right, title and interest in, the option and the shares issuable upon exercise thereof.
Option grant size 17,096 shares Underlying common stock for new stock option grant
Exercise price $6.69/share Conversion or exercise price of stock option
Expiration date June 8, 2036 Stock option expiration
Vesting date June 9, 2027 Earlier of this date or next Annual Meeting of Stockholders
Post-grant derivative holdings 17,096 options Total derivative securities following transaction
Stock Option (Right to Buy) financial
"security_title: "Stock Option (Right to Buy)""
derivative security financial
"transaction_type: "derivative" for the stock option grant"
A derivative security is a financial contract whose value comes from the price or performance of something else, such as a stock, bond, commodity, or market index. For investors it acts like an insurance policy or a wager: it can be used to protect against losses, lock in prices, or amplify gains and losses, so it can change a portfolio’s risk and potential return without owning the underlying asset directly.
beneficial ownership financial
"Mr. Fleming disclaims beneficial ownership of, and all right, title and interest"
Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.
Annual Meeting of Stockholders financial
"earlier of June 9, 2027 and the date of the next Annual Meeting of Stockholders"
exercise price financial
"conversion_or_exercise_price of $6.6900 per underlying share"
The exercise price is the fixed amount at which you can buy or sell an asset, like a stock, when using an options contract. It matters because it helps determine whether exercising the option will be profitable or not, depending on the current market price. Think of it as the set price you agree on today to buy or sell later.
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SEC Form 4
FORM 4UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940
OMB APPROVAL
OMB Number:3235-0287
Estimated average burden
hours per response:0.5
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.
1. Name and Address of Reporting Person*
Fleming Harold Edward

(Last)(First)(Middle)
UPSTREAM BIO, INC.
890 WINTER STREET, SUITE 200

(Street)
WALTHAM MASSACHUSETTS 02451

(City)(State)(Zip)

UNITED STATES

(Country)
2. Issuer Name and Ticker or Trading Symbol
Upstream Bio, Inc. [ UPB ]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
XDirector10% Owner
Officer (give title below)Other (specify below)
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
06/09/2026
6. Individual or Joint/Group Filing (Check Applicable Line)
XForm filed by One Reporting Person
Form filed by More than One Reporting Person
4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year)2A. Deemed Execution Date, if any (Month/Day/Year)3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4)
CodeVAmount(A) or (D)Price
Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year)3A. Deemed Execution Date, if any (Month/Day/Year)4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 6. Date Exercisable and Expiration Date (Month/Day/Year)7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Stock Option (Right to Buy)$6.6906/09/2026A17,096 (1)06/08/2036Common Stock17,096$017,096D(2)
Explanation of Responses:
1. The shares underlying this option shall vest in full upon the earlier of (i) June 9, 2027 and (ii) the date of the next Annual Meeting of Stockholders of the Issuer, subject to the Reporting Person's continued service on such vesting date.
2. Mr. Fleming has agreed to receive and hold for the benefit of Enavate Sciences, LP, any securities granted to him for his service as a director on the Issuer's board of directors. As such, Mr. Fleming disclaims beneficial ownership of, and all right, title and interest in, the option and the shares issuable upon exercise thereof.
/s/ Allison Ambrose, Attorney-in-Fact06/11/2026
** Signature of Reporting PersonDate
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)

FAQ

What did Harold Edward Fleming report in this Upstream Bio (UPB) Form 4?

Harold Edward Fleming reported receiving a stock option grant for 17,096 shares of Upstream Bio common stock. The option is compensation for his board service and represents a right to buy shares at a fixed exercise price in the future, subject to vesting.

What are the key terms of the Upstream Bio (UPB) stock option granted to Harold Edward Fleming?

The stock option covers 17,096 underlying common shares with a $6.69 exercise price and expires on June 8, 2036. It is a derivative security labeled as a “Stock Option (Right to Buy)” and was reported as a grant, award, or other acquisition.

When do Harold Edward Fleming’s Upstream Bio (UPB) options vest?

The options vest in full on the earlier of June 9, 2027 or the date of Upstream Bio’s next Annual Meeting of Stockholders. Vesting is conditioned on Mr. Fleming’s continued service as a director through the applicable vesting date, as described in the footnote.

Who ultimately benefits from the Upstream Bio (UPB) option grant reported by Harold Edward Fleming?

Although granted in Mr. Fleming’s name, he has agreed to receive and hold the securities for the benefit of Enavate Sciences, LP. He disclaims beneficial ownership and all right, title, and interest in the option and the shares issuable upon exercise.

How many Upstream Bio (UPB) derivative securities does the Form 4 show after this transaction?

After the reported grant, the Form 4 shows Mr. Fleming with 17,096 derivative securities in the form of stock options. These represent rights to acquire the same number of common shares at the stated exercise price, subject to vesting and expiration terms.